Coding of originals and sensitive paper in a multi-color electrophotographic process

ABSTRACT

The provision of corresponding codes on originals and sensitive paper employed in the production of multi-colored copies by an electrophotographic process. The codes enable multiple copies of one color to be prepared before incorporation of further colors, by excluding any possibility of a mismatch between original and sensitive paper during subsequent exposures.

United States Patent Matsumoto [451 Apr. 18, 1972 [54] CODING OFORIGINALS AND [56] References Cited SENSITIVE PAPER IN A MULTI-COLORUNITED STATES PATENTS ELECTROPHOTOGRAPHIC PROCESS 3,057,720 10/1962Hayford et al. ..96/l.2 x [721 i siif'fMasmfesaiamelapan 311212;? 35132;ESQ-525K331: tiffiii Asslgneel f l Photo Fllm Kanagawa, 3,307,458 3/1967Hunstiger et a1 ..355/4 X apan - Primary Examiner-George F. Lesmes [22]Filed 1970 Assistant Examiner-John R. Miller [2i] Appl. No.: 26,348Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak 30 Foreign ApplicationPriority Data [57] ABSTRACT v The provision of corresponding codes onoriginals and sensi- Apr. 8, Japan five p p p y in the production fmulti colored copies by an electrophotographic process. The codes enablemultiple [52] U.S.Cl ..96/l.2, 355/4 copies of one color to be preparedbefore incorporation of G03g13/00 further colors, by excluding anypossibility of a mismatch Field of Search 6/ l.2; 355/4 between originaland sensitive paper during subsequent exposures.

4 Claims, 10 Drawing Figures CODING OF ORIGINALS AND SENSITIVE PAPER INA MULTI-COLOR ELECTROPIIOTOGRAPHIC' PROCESS BACKGROUND OF THE INVENTION1 Field of the Invention This invention relates to anelectrophotographic process. More particularly, it relates to amulti-color electrophotographic process involving two or more colors.

2. Description of the Prior Art There-is knownin the art an'electrophotographic. process which comprises the steps of electricallycharging an electrophotographicsensitive paper having a photo-conductiveinsulative layer by means of the well-known corona dischargeor othersimilar method, exposing the paper to light through an image, formingthereon an electrostatic pattern (hereinafter referred to aselectrostatic image.) and. depositing toner powder on the sensitivepaper in conformity to the electrostatic image, either by bringing thepaper intoclose proximity with electrically charged, colored fine powder(hereinafter referred to as toner) or bringing it into contact with aninsulative liquid having toner dispersed therein (hereinafter referredto as liquid developing agent). Two or more toners of different colorsare adhered to the sensitive paper by repeating the steps of electriccharging, exposure to light, and development as many times as required.

In such electrophotographic processes, proper registration of thevarious colored images constitutes an important problem. In exposing a.sensitive paper to light through a colored original imageinvolving theuse of cyan and magenta yellow pigments, for example, theelectrophotographic sensitive paper is electrically-charged with respectto the first color, exposed to light through the image via a filter forthe first color, and subjected to a first development. The sensitivepaper is then electrically chargedwith respect to the second color andsubjected toa second development through a filter for the second color.Similarly, an image composed of a number of toners havingdifferentcolors can be obtained by repetition of this procedure. In such aprocess, after the sensitive paper is exposed tolight projected throughthe original for the purpose of exposing it to the image, a firstdevelopment is carried out and completed for the first color prior tofurther processing. Thus, the light projector cannot be used again untilthe development is completed. Since, therefore, the light projector ismade to stand unused=during the interval between the completion of thefirst development and the second exposure to light which follows thestep of electrically charging the sensitive paper, the operating ratioof the machine (the proportion of time it is actually in use duringtheprocess) is very low.

When many originals are reproduced simultaneously so as to eliminate theabove shortcoming, the first original is mounted on the projector toeffect the necessary exposure and the sensitive paper subjected to thisexposure (to be called first sensitive paper") is forwarded todevelopment. The first original is then removed from the projector andthe second original is immediately mounted thereon to effect exposure onthe second sensitive paper, which is then immediately forwarded todevelopment. This procedure is repeated until the nth original ismounted on the projector and the nth sensitive paper is subjected toexposure and forwarded to development. In this manner, theelectrophotographic process for one color can be efiiciently effected onmany originals, maintaining the operating ratio of the machine high.

2 vention proposes to Subsequently, the same electrophotographic processcan be II. Once an electrophotographic sensitive layer is exposed tolight, it has a tendency to retain residual photoconductive effects,even after exposure. However, when many sensitive papers are developedcontinuously for one color, they are maintained in a dark place for asufficient time to achieve complete recovery from such residual effects.Consequently, suchpapers are very stable in this regard.

When sensitive papers-which have undergone the development with thefirst color are subsequently exposed to light with the second color,however, the originals used must correspond exactly to those used in thedevelopment with the first color. Otherwise, up to several hundreds ofuseless copies may be obtained by the possible mismatching of originalsand papers.

SUMMARY OF THE INVENTION With a view to preventing such confusion, thepresent inprovide an identifying code, corresponding to the original,struck or written on the sensitive paper at the time of exposure usingthe first color, so that, at the time of exposure using the second andsubsequent colors, agreement between the sensitive papers andtheoriginals may be sensed by virtue of such codes. Upon detection of alack of agreement, there will be issued an alarm signal or,alternatively, the machine will be brought to a stop. This sameprinciple can be applied to the use of a roll of sensitive paper byregarding the first exposure frame as the first sensitive paper and thenth exposure frame as the nth sensitive paper, etc.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents a perspective viewillustrating the manner in which the present invention is executed.

FIG. 2 is a perspective view of the mount for the original to be used inthe present invention.

FIG. 3 is a cross-sectional view along line A-A of FIG. 2.

FIG. 4 illustrates a mechanism for reading the code of the originalmount.

FIGS. 5 and 6 illustrate a device for transferring the original mountonto the sensitive paper.

FIG. 7 illustrates one example of circuitry for setting the code.

FIG. 8 illustrates mechanism usable concurrently for reading and writingthe code.

FIG. 9 is a perspective view illustrating one example of a roll ofsensitive paper having the code thereon.

FIG. 10 is a side elevation illustrating such a roll of sensitive paperon which the present invention is being executed.

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanyingdrawings in more detail, FIG. 1 represents a manner of exposing to lightan electrically charged sensitive paper. In the Figure, 1 denotes alight source for exposure, 2 is a frame for mounting an original, and 10is an original composed of a plurality of colors. By means of projectinglens 3, the image on the original is projected through a color-resolvingfilter 11, as shown by 8, onto a sensitive paper 4, with a result thatthere is formed an image of one color resolution. Denoted by 9 and 9'are the holes which serve to enable the original to be held at a fixedposition. By virtue of these holes, originals can be laid in a fixedposition. The numerals 7 and 7 denote the pins provided on the base 12for the purpose of obtaining proper register. Holes are punched in thesensitive paper corresponding to these pins so that the sensitive papercan be laid in the same fixed position at all times.

The numeral 5'denotes a code applied to the mount of the original. Topermit discrimination of one mount from another, each has a differentcode. This code may be in the form of punched holes which may be sensedby means of pins, or it may be in the form of prints to be read out bymeans of photoelectric tubes. The numeral 6 denotes a code formed on thesensitive paper corresponding to that of mount 5. The

code is placed in an area of the sensitive paper other than that usedfor the formation of an image. The code may be punched holes or coloredmarks. The code may also be formed by imparting an electrostatic imageon the sensitive paper at the time of exposure with the first color andconverting it into a colored mark by utilizing the development of thefirst color.

At the time of first exposure, code 6 is recorded in conformity to codewhich is placed on the original mount. At

the time of the second and subsequent exposures, code 5, on the originalmount, and code 6, on the sensitive paper, are compared. When they arein agreement, the sensitive paper is subjected to exposure and thenforwarded to the development step.

However, should the two codes not be in agreement, the process isstopped and an alarm is issued.

In this manner, duplicates can be produced from numerous originalsefficiently and safely, with heightened machine operating ratios.

FIG. 2 illustrates an original mount as one embodiment of the presentinvention. In this figure, a mult i-color original 10 is mounted andfixed on mount 2. Numeral denotes a hinge which may be utilized forremoving the original from the mount. 17 is a holder for the original,and 16 is a clip which holds holder 17 and mount 2 together. Of course,one original is held in the same mount throughout the entire procedure.In other words, one mount is prepared for each original and the originalheld in one mount is handled as one original. Therefore, discriminationbetween originals is accomplished by means of codes in these mounts.Numeral 5 denotes a code comprised of holes formed on the illustratedmount. One example of a coding system which may be employed is onewherein a hole may be punched or unpunched at each of a total of eightplaces. Using such a system, there may be prepared 2 mounts which can bediscriminated from one another.

FIG. 4 illustrates a device for sensing code 5 on mount 2. The drawingis intended to show the working of the device sensing the presence orabsence of a coded hole at a given position. In this device, 20 denotesa microswitch and 21 an actuator thereof which is raised or lowereddepending upon the presence or absence of a coded hole in a givenposition. Where a hole is present, the actuator falls, as indicated bydotted lines 22, turning the microswitch, for example, from OFF to ON.

FIG. 5 illustrates a device for transferring the sensed code onto thesensitive paper. Solenoid 30 pushes up punch 31 so as to punch a hole insensitive paper 4 which is laid on the base 33. Denoted by 32 is a holein the base provided for insertion of the point of the punch.

The devices shown in FIG. 4 and 5 are combined as a pair, and anyrequired number of such pairs may be arranged in a row to form a systemusable for transferring code 5 from the mount onto the sensitive paper.

FIG. 6 illustrates a device, similar to that of FIG. 4, adapted to readthe code from the sensitive paper during the course of second andsubsequent processing. This device is so constructed that the sensingpunch is situated at the same position as the punch of FIG. 5. In thedrawing, 35 denotes a microswitch and 36 the actuator thereof. Theactuator senses the presence or absence of a hole and turns themicroswitch ON or OFF accordingly.

FIG. 7 illustrates one example of circuitry which may be employed forthe sensing of codes. In this figure, there is shown a circuit includinga microswitch contact arm 40 connected to the code 5 sensing means (e.g.20 of FIG. 4) and a microswitch contact arm 41 connected to the code 6sensing means (e.g. 30 of FIG. 5) connected by two lead wires.

Assuming a sensitive paper in which is punched holes in the same patternas that of the code holes on the mount and, assuming further that theposition of arm 40 represents the presence of a hole punched in themount and that the position of arm 41 represents the presence of a codehole in the sensitive paper. In this case, since the code holescorrespond, the circuit is not connected. If no hole is present on thesensitive paper, arm 41 will be positioned as shown by dotted line 44.The circuit would then be connected to permit electric current to flowfrom source 43 to the device for stopping the process or to the alarmsystem and actuate such device. By arranging any required number of suchpairs, erroneous combinations of mounts with sensitive papers can bequickly detected and possible loss of materials can be prevented. Itwill be obvious to the skilled practitioner in this art, of course, thatalternative designs could be employed. For example the operation of themicroswitches could be arranged so as to permit the flow of power to theexposing device only a proper combination of original and sensitivepaper is present.

FIG. 8 illustrates a device by which the code holes may be punched inand read from the sensitive paper by one and same device. In the firstcolor step, the solenoid is operated to open holes on the sensitivepaper 4 in accordance with the code 5 on the original mount. In thesecond and subsequent process, the pressure exerted by the solenoid isadjusted downwards so that, where the hole is absent on the sensitivepaper, arm 37 is stopped by the pin provided at the tip of punch arm 37,

whereas the arm is allowed to continue further down in the presence of ahole, with the consequence that the movement thereof will be detected bymicroswitch 39. By means of this principle, one and same device canaccomplish both the punching and reading of the code through adjustmentof the strength of the solenoid.

Up to this point, the description has concerned only the use of codescomposed of punched holes. However, besides using punched holes ascodes, combinations of coded areas having different reflecting powersmay be used as codes and sensed by photoelectric tubes as a matter ofcourse.

' FIG. 9 illustrates acase in which a plurality of coded areas arereproduced on a roll of sensitive paper 4. In the figure, 50, 50 and 50"denote a row of drawings and 6 and ,6 denote the codes which are placedon the boundaries thereof. These codes, 6 and 6' may be combinations ofpunched holes or of colored elements. In the case of using coloredelements, exposure may be regulated according to the codes and the codesmay be obtained by development in the first process.

FIG. 10 illustrates a process involving the use of a roll of sensitivepaper. By means of charging device 51, sensitive paper 4 is electricallycharged and in the first color step, the codes are recorded by device52. In the second and subsequent color steps, the codes are read out bydevice 52 and compared with the codes on the mounts.

As mentioned above, the method of the present invention provides asolution to problems intrinsic in the preparation of multi-color printsin electrophotography. Particularly, since electrophotography involvesthe processes of overlaying exposures and developments, preciseregistration of the sensitive paper with the original at the time ofexposure is indispensable. Thus, the mechanism for exposure mustincorporate means for positional registration. Incorporation of asensing means with respect to individual frames in a roll of sensitivepaper proves to be one advantageous embodiment of the present invention.

What is claimed is:

1. In an electrophotographic process for forming an image of two or morecolors on the same sensitive paper comprising:

a. exposing a first sensitive paper to a first original, mounted on aprojector, of a first color and developing said first color in saidfirst sensitive paper;

b. immediately after said first sensitive paper is exposed in step (a),removing said first original of said first color from said projector,mounting thereon a second original of said first color, exposing asecond sensitive paper to said second original of said first color anddeveloping said first color in said second sensitive paper;

c. repeating steps (a) and (b) for n sensitive papers using n originalsof said first color, wherein n can be zero or a positive integer;

d. exposing said first sensitive paper having an image of said firstcolor thereon to said first original of a second color,

mounted on said projector, and developing said second color in saidfirst sensitive paper;

. immediately after said first sensitive paper is exposed in step (d),removing said first original of said second color from said projector,mounting thereon a second original of said second color, exposing saidsecond sensitive paper having an image of said first color thereon tosaid second original of said second color and developing said secondcolor in said second sensitive paper; repeating steps (d) and (e) forsaid n sensitive papers using n originals of said second color, whereinn has the above meaning, to thereby obtain (2+n) sensitive papers eachhaving an image of said first and second colors thereon; and

g. repeating steps (d), (e) and (f) for each additional color desired;

the improvement comprising, in the first exposing step of each originalof said N originals of said first color, providing a code, correspondingto a code associated with each original of the image, on the sensitivepaper whereon there is formed the image and, in subsequent exposingsteps, collating the code associated with the original with the codeprovided on the sensitive paper, whereby subsequent exposure of thepaper is allowed to occur only when the two codes are identical, therebyassuring that each of said sensitive papers, having a colored imagethereon, is properly aligned for subsequent exposure to another originalof the same image but of different color.

4. The process of claim 3 wherein said sensitive paper comprises acontinuous roll, the first exposure frame thereof corresponding to thefirst sensitive paper and the nth exposure frame corresponding to thenth sensitive paper.

3. The process of claim 3 wherein the code is formed by imparting anelectrostatic image onto the sensitive paper at the time of exposurewith the first color and converting it into a colored mark by utilizingthe development of the first color.

4. The process of claim 3 wherein a multiplicity of images are formed ona single sensitive paper and wherein the provided code is placed at aposition of the sensitive paper corresponding to each individual image.

3. The process of claim 3 wherein the code is formed by imparting anelectrostatic image onto the sensitive paper at the time of exposurewith the first color and converting it into a colored mark by utilizingthe development of the first color.
 4. The process of claim 3 whereinsaid sensitive paper comprises a continuous roll, the first exposureframe thereof corresponding to the first sensitive paper and the nthexposure frame corresponding to the nth sensitive paper.
 4. The processof claim 3 wherein a multiplicity of images are formed on a singlesensitive paper and wherein the provided code is placed at a position ofthe sensitive paper corresponding to each individual image.